As described in, for example, the patent documents 1-5 below, there are commonly used display devices which divide a frame for one screen into plural sub frames by time division. According to the documents, the quality of moving images is improved such that impulse-type light emission typified by CRTs (Cathode-Ray Tube) is simulated by a hold-type display device such as a liquid crystal display device by providing a black display or dark display period in one frame period.
Also, as taught by the patent document 6 below, the response speed of a liquid crystal display device is improved by modulating a drive signal in such a way as to emphasize grayscale transition between two frames.
[Patent Document 1]
Japanese Unexamined Patent Publication No. 302289/1994 (Tokukaihei 4-302289 published on Oct. 26, 1994)
[Patent Document 2]
Japanese Unexamined Patent Publication No. 68221/1995 (Tokukaihei 5-68221; published on Mar. 19, 1995)
[Patent Document 3]
Japanese Unexamined Patent Publication No. 2001-281625/2001 (Tokukai 2001-281625; published on Oct. 10, 2001)
[Patent Document 4]
Japanese Unexamined Patent Publication No. 23707/2002 (Tokukai 2002-23707; published on Jan. 25, 2002)
[Patent Document 5]
Japanese Unexamined Patent Publication No. 22061/2003 (Tokukai 2003-22061; published on Jan. 24, 2003)
[Patent Document 6]
Japanese Patent No. 2650479 (issued on Sep. 3, 1997) [Non-Patent Document 1]
Handbook of Color Science; second edition (University of Tokyo Press, published on Jun. 10, 1998)